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T J Thompson

Publications and source records attributed to T J Thompson.

At least 19 recordsLinked to original sources
PubMed1997

A model for interval-censored tuberculosis outbreak data.

As the incidence of tuberculosis (TB) has increased in the United States, occupationally acquired TB has increased among the health care workers (HCWs). This paper describes a model developed in response to the needs of an outbreak of multidrug-resistant TB. One of the goals of the outbreak investigation was to estimate the risk of tuberculin skin test (TST) conversion as a function of HCW job type and the period during which persons were employed over the study period. TST conversions were evaluated at periodic examinations and data are interval-censored. We present a generalized linear model that extends Efron's survival model for censored survival data to the case of interval-censored data.

Bias↗
PubMed1997

Comparison of fasting and 2-hour glucose and HbA1c levels for diagnosing diabetes. Diagnostic criteria and performance revisited.

OBJECTIVE: Nearly two decades ago, the National Diabetes Data Group (NDDG) and the World Health Organization (WHO) Expert Committee on Diabetes Mellitus published diagnostic criteria for diabetes. We undertook this study to compare the performance of three glycemic measures for diagnosing diabetes and to evaluate the performance of the WHO criteria. RESEARCH DESIGN AND METHODS: In a cross-sectional population-based sample of 1,018 Egyptians > or = 20 years of age, fasting and 2-h glucose and HbA1c levels were measured, and diabetic retinopathy was assessed by retinal photograph. Evidence for bimodal distributions was examined for each glycemic measure by fitting models for the mixture of two distributions using maximum likelihood estimates. Sensitivity and specificity for cutpoints of each glycemic measure were calculated by defining the true diabetes state (gold standard) as 1) the upper (diabetic) component of the fitted bimodal distribution for each glycemic measure, and 2) the presence of diabetic retinopathy. Receiver operating characteristic (ROC) curves were constructed to determine the performance of the glycemic measures in detecting diabetes as defined by diabetic retinopathy. RESULTS: In the total population, the point of intersection of the lower and upper components that minimized misclassification for the fasting and 2-h glucose and HbA1c were 7.2 mmol/l (129 mg/dl), 11.5 mmol/l (207 mg/dl), and 6.7%, respectively. When diabetic retinopathy was used to define diabetes, ROC curve analyses found that fasting and 2-h glucose values were superior to HbA1c (P < 0.01). The performance of a fasting glucose of 7.8 mmol/l (140 mg/dl) was similar to a 2-h glucose of 12.2-12.8 mmol/l (220-230 mg/dl), and the performance of a 11.1 mmol/l (200 mg/dl) 2-h glucose was similar to a fasting glucose of 6.9-7.2 mmol/l (125-130 mg/dl). CONCLUSIONS: Optimal cutpoints for defining diabetes differ according to how diabetes itself is defined. When diabetes is defined as the upper component of the bimodal population distribution, a fasting glucose level somewhat lower than the current WHO cutpoint and a 2-h glucose level somewhat higher than the current WHO cutpoint minimized misclassification. When diabetic retinopathy defines diabetes, we found that the current fasting diagnostic criterion favors specificity and the current 2-h criterion favors sensitivity. These results should prove valuable for defining the optimal tests and cutpoint values for diagnosing diabetes.

Adult↗
PubMed1996

A generalized linear model for analysing receiver operating characteristic curves.

We present a continuation ratio model for analysing ordinal categorical data and we apply the model to the problem of estimating receiver operating characteristic (ROC) curves. We apply the methods to post-prandial capillary blood glucose measurements as a criterion for a potential screening test for diabetes mellitus. One can obtain point estimates of sensitivity and specificity and their associated standard errors at any value along the observed range of post-prandial capillary blood glucose measurements. Also, in comparison to the models for ROCs described by Tosteson and Begg, ROC curves based on the continuation ratio model have the desired features that allow ROCs to be concave but not necessarily symmetric.

Adult↗
PubMed1996

The onset of NIDDM and its relationship to clinical diagnosis in Egyptian adults.

The onset of diabetes relative to clinical diagnosis was estimated in Egyptians with non-insulin-dependent diabetes mellitus (NIDDM) based on the relationship between retinopathy and duration of diabetes. Between July 1992 and October 1993 the Diabetes in Egypt (DIE) Project performed a cross-sectional, population-based survey with clinical and laboratory follow-up to describe the prevalence of microvascular, neuropathic, and macrovascular complications among Egyptians > or = 20 years of age with diagnosed diabetes, previously undiagnosed diabetes, impaired glucose tolerance, and normal glucose tolerance. The sample of persons with diabetes diagnosed prior to the survey had medical examinations which included a dilated eye examination and retinal photographs. Generalized linear models were used to relate the probability of retinopathy to duration of diabetes. Among 218 persons with diabetes diagnosed prior to the DIE project, 87 (40%) had diabetic retinopathy. The onset of retinopathy was estimated to occur 2.6 years (p = 0.04) prior to clinical diagnosis. The estimated annual incidence of retinopathy was 5% and the estimated prevalence at the time of clinical diagnosis of diabetes was 12%. On the basis of reports that retinopathy does not occur until approximately 5 years after the development of diabetes, the onset of NIDDM was estimated to occur 7.6 years prior to its clinical diagnosis. This estimate of the onset of NIDDM in Egyptians is comparable to other estimates reported for US and Australian populations.

Adult↗
PubMed1995

Screening for NIDDM in nonpregnant adults. A review of principles, screening tests, and recommendations.

The economic burden of diabetes in the U.S. is now more than 90 billion dollars per year (113-115). In the diabetes community, there is a feeling that aggressive measures to detect diabetes in earlier stages may be warranted. Regardless of whether evidence is convincing that there are benefits from early detection of diabetes (3,116,117), screening activities have been sanctioned by many organizations and are now taking place. Operational research is needed to define more clearly the who, when, where, and how of screening and the effectiveness of screening programs (4,118). Diabetes screening programs should be comprehensive and should educate about diabetes and provide appropriate interpretation of both positive and negative screening results. It is essential that programs have diagnostic follow-up and refer those with newly diagnosed diabetes for treatment. In addition, individuals with previously diagnosed diabetes encountered during screening activities should be made aware of the importance of glycemic control and follow-up with their health care providers.

Adult↗
PubMed1995

A new and simple questionnaire to identify people at increased risk for undiagnosed diabetes.

OBJECTIVE: To develop a simple questionnaire to prospectively identify individuals at increased risk for undiagnosed diabetes. RESEARCH DESIGN AND METHODS: People with newly diagnosed diabetes (n = 164) identified in the Second National Health and Nutrition Examination Survey and those with neither newly diagnosed diabetes nor a history of physician-diagnosed diabetes (n = 3,220) were studied. Major historical risk factors for undiagnosed non-insulin-dependent diabetes were defined, and classification trees were developed to identify people at higher risk for previously undiagnosed diabetes. The sensitivity, specificity, and predictive value of the classification trees were described and compared with those of an existing questionnaire. RESULTS: The selected classification tree incorporated age, sex, history of delivery of a macrosomic infant, obesity, sedentary lifestyle, and family history of diabetes. In a representative sample of the U.S. population, the sensitivity of the tree was 79%, the specificity was 65%, and the predictive value positive was 10%. CONCLUSIONS: This classification tree performed significantly better than an existing questionnaire and should serve as a simple, noninvasive, and potentially cost-effective tool for diagnosing diabetes in the U.S.

Adult↗
PubMed1995

Screening for diabetes mellitus in adults. The utility of random capillary blood glucose measurements.

OBJECTIVE: Because half of the people with non-insulin-dependent diabetes mellitus (NIDDM) are undiagnosed and because near-normal glycemic control can prevent diabetic complications, we evaluated the use of field-based random capillary blood glucose measurement as a screening test for NIDDM. RESEARCH DESIGN AND METHODS: A cross-sectional sample of 828 Egyptians > or = 20 years of age underwent both a random capillary blood glucose measurement performed with a portable reflectance meter in the field and an oral glucose tolerance test in the laboratory. The sensitivity and specificity of random capillary blood glucose measurements in predicting the presence of NIDDM were evaluated. RESULTS: Multivariate analyses showed that the screening test performed better when subjects had eaten shortly before the test (area under receiver operating characteristic curve, 0.87 for a 1-h postprandial period compared with 0.69 for an 8-h postprandial period) and that the optimal capillary blood glucose cutoff points to define a positive test increased with age. For a postprandial period of 1 h, cutoff points of 115 mg/dl for individuals 30 years of age and 140 mg/dl for those 75 years of age yielded similar performance characteristics (sensitivity 82% and specificity 78% for those 30 years old; sensitivity 81% and specificity 80% for those 75 years old). CONCLUSIONS: Adjusting random capillary blood glucose measurements for the postprandial period and using age-specific cutoff point values can improve performance of the screening test.

Adult↗
PubMed1991

Diabetic end stage renal failure--the Wellington experience 1975-1988.

Since the late 1970s patients with diabetic nephropathy have formed an increasing proportion of new entrants to the Hospital renal dialysis and transplantation programme, reaching 28% for the three year period to December 1988. Between 1 January 1975 and 31 December 1988, 87 diabetic patients were accepted for treatment. Fifty-one per cent were European, predominantly type I diabetics. Maori (9% of the total reference population) accounted for a disproportionately high 47% due to an over-representation by type II diabetic patients (34 of 41 Maori). These findings cannot be explained by the higher prevalence in Maori of type II diabetes but appear to be due to a more prevalent and/or aggressive diabetic renal lesion in this group. On commencing treatment, nearly all patients had retinopathy and the majority had evidence of peripheral vascular disease, hypertension and neuropathy. CAPD was the initial mode of renal replacement therapy in 70% of patients. Overall patient survival was 77% at one year and 42% at three years, and survival on CAPD was 76% and 37% at one and three years, respectively. Patient survival on transplantation was 63% at one year and 58% at three years. Graft survival was 51% at one year and 46% at three years. Although the short term outlook for diabetic patients on renal replacement therapy is encouraging, longer term survival compared to non-diabetic patients is poor. Vascular disease is the major cause of death and an important factor in patient morbidity.

Adult↗
PubMed1991

Improving accuracy in documentation of restrictive interventions by direct-care personnel.

Accurate and reliable documentation of rights restrictions is critical for evaluating a program's success against the intrusiveness of a behavioral intervention, complying with regulatory standards, and refining treatment strategies. Direct-care and ancillary staff in three cottages at a state facility for persons with mental retardation were selected to evaluate a revised documentation system, including a new form, inservice training for staff inservice, and staff feedback, that was implemented sequentially across cottages. Results showed an immediate and sustained reduction in documentation errors following the implementation of the documentation system. Benefits and limitations of the new system were discussed.

Adult↗
PubMed1989

Quinidine enhancement of digoxin toxicity in rats and minipigs.

The combined use of digoxin and quinidine has been associated with potentially fatal toxic reactions. The mechanisms involved in this drug interaction were investigated in Wistar rats and Hormel miniature pigs (minipigs). Infusions of digoxin alone (0.013 mg/min) and in combination with quinidine (0.051 mg/min) demonstrated that quinidine pretreatment significantly decreases the time of onset of arrhythmias and death in these animals as compared with digoxin alone. Similarly, when administered as a slow, bolus intravenous (i.v.) injection to either anesthetized or unanesthetized minipigs, quinidine pretreatment (10 mg/kg, i.v.) led to the rapid development of arrhythmias and death. Quinidine administration in both species also causes a dramatic reduction in blood pressure, and it appears that this hypotension may trigger the irregular rhythms of the heart once digoxin is administered. Electrocardiographic (ECG) evidence showed that the toxicity associated with digoxin administration alone was characterized by bradyarrhythmias and death was attributed to cardiac arrest. In contrast, quinidine pretreatment led to severe tachyarrhythmias and earlier death by ventricular fibrillation. These studies demonstrate the usefulness of these two species, particularly the minipigs, in assessing the magnitude of this drug interaction and also confirm the risks involved when these two drugs are combined.

Anesthesia↗
PubMed1989

Acute perirenal lymphocele formation 8 years after renal transplantation.

The majority of lymphoceles forming as a result of renal transplantation present or are detected within 6 months of surgery. A rare case of late presentation is reported, where the lymphocele developed 8 years after renal transplantation, due to leakage of lymph from the transplant kidney surface.

Adult↗
PubMed1989

Intramembranous osteogenesis and angiogenesis in the chick embryo.

Membrane bone formation was examined in the developing chick frontal bone of Stage 32-36 embryos using alizarin red whole mounts, wax and resin histology, transmission electron microscopy and India ink injection techniques. Mineralised bone was seen at Stage 36, but was presaged by the appearance of twin mesenchymal condensations at Stage 35. The condensations appeared dorsolateral to the upper edge of the interorbital septum near its centre. The mesenchymal cells of the condensation were fusiform in shape and initially exhibited a close-packed, layered configuration which was avascular. Consequent differentiation of the central cells first into preosteoblasts and then into definitive osteoblasts, accompanied by secretion of bone matrix, coincided with blood vessel invasion of the frontal anlagen. It is suggested that these vascular changes associated with the onset of bone cell differentiation indicate that osteogenic cells may secrete an angiogenesis factor.

Animals↗
PubMed1985

Stereotyped behavior of severely disabled children in classroom and free-play settings.

The relationships between stereotyped behavior, object manipulation, self-manipulation, teacher attention, and various developmental measures were examined in 101 severely developmentally disabled children in their classrooms and a free-play setting. Stereotyped behavior without objects was positively correlated with self-manipulation and CA and was negatively correlated with complex object manipulation, developmental age, developmental quotient, and teacher attention. Stereotyped behavior with objects was negatively correlated with complex object manipulation. Partial correlations showed that age, self-manipulation, and developmental age shared unique variance with stereotyped behavior without objects.

Adolescent↗
PubMed1984

The effect of week-long infusion of propranolol, via an osmotic minipump, on blood pressure, heart rate and vascular responses in spontaneously hypertensive rats.

Propranolol was infused in SHR subcutaneously for 7 days at two concentrations (either 3.75 or 7.5 mg kg-1 day) via a minipump. Mean blood pressure and heart rate measured under pentobarbitone anaesthesia on day 7 after implantation showed a significant dose-dependent decrease in both propranolol-treated groups. In the low-dose propranolol-treated rats, there was no change in contractile responses to phenylephrine over controls. In rats receiving the higher dose of propranolol there was a significant increase in the response to phenylephrine. There was no change in the relaxation response of any of the groups to isoprenaline. The results indicate that propranolol, while lowering blood pressure and heart rate, is also modifying the alpha-receptor response of the vascular wall in the spontaneously hypertensive rat.

Animals↗
PubMed1982

Training and generalization of laundry skills: a multiple probe evaluation with handicapped persons.

An instructional procedure composed of a graded sequence of prompts and token reinforcement was used to train a complex chain of behaviors which included sorting, washing, and drying clothes. A multiple probe design with sequential instruction across seven major components of the laundering routine was used to demonstrate experimental control. Students were taught to launder clothing using machines located in their school and generalization was assessed later on machines located in the public laundromat. A comparison of students' laundry skills with those of normal peers indicated similar levels of proficiency. Follow-up probes demonstrated maintenance of laundry skills over a 10-month period.

Adolescent↗
PubMed1978

Impact of drug information services on patient care.

The use of information provided by the Drug Information Service of the University of Connecticut Health Center and its effect on patient care were investigated. All drug information requests received during the period from May 1 to August 15, 1977, were reviewed and followed up to determine (1) the usefulness of the information provided, (2) specific outcome(s) of applying the information to a patient-specific problem and (3) the ultimate effect of these outcomes on the patient. A total of 491 requests were received and 443 (90%) of these were followed up. Of those followed up, 421 (95%) were related to patient care. Of the 421 requests related to patient care, 350 (83%) were patient-specific. Of the 350 patient-specific requests, 329 (94%) were judged by the requestors to have provided useful information. Of these 329 requests, 202 (58%) resulted in provision of information that affected patients' outcomes, of which 157 (78%) had positive effects on patients. It is concluded that (1) the drug information center is providing useful information to health professionals, (2) the information is being applied to patient-specific problems and (3) use of the information is having a positive impact on patient care.

Connecticut↗